Field of the Invention
The present invention relates to an image projection apparatus capable of performing electronic zooming.
Description of the Related Art
A liquid crystal projector (image projection apparatus) is an apparatus which modulates light beams emitted from a light source depending on image information to form an optical image and magnifies the optical image by using a projection lens to project the magnified image on a screen. When the image is to be projected on a large screen, the liquid crystal projector is mounted on a ceiling with some installation distance in many cases. When a rear projection is to be performed from a back of a screen, a wide-angle end focal lens is used.
Japanese Patent Laid-open No. 2012-128056 discloses a display apparatus which shifts a lens to align positions of the centers of images when receiving a zoom instruction. Japanese Patent No. 3722146 discloses a projector which deforms a projection area so that a circumference of a projection area contacts a circumference of a projection plane with at least one contact point by using a zoom processing unit of the projection image and a keystone correcting unit.
However, when the zooming is performed for the projection area by using a lens-interchangeable liquid crystal projector, a luminance of the projection image varies depending on a shift position of a lens. Therefore, in order to obtain a high-luminance projection image, it is necessary to perform appropriate zooming depending on the shift position of the lens. When a fixed focal lens is used, it is preferred that electronic zooming is performed, instead of optical zooming, to align angles of view in some cases.